Sensor or combined sensor-munition field units (“field units”), such as wide area munitions, are commonly distributed across a predefined region of a defensive position. Such units are deployed according to a number of techniques, including scattering from an air position, dropping from a moving truck, or hand-placement by installation personnel. Upon deployment, a field unit is required to right itself so that sensors can begin to sweep for threats or targets of interest.
A field unit may include a large upper body, e.g., in the shape of a canister, that is suspended above a lower base. The base may include various mechanisms for rotating and positioning the upper body. A plurality of feet or legs are typically released from the base for righting and stabilizing the unit. The upper body houses various systems which may include, for example, a munition or plurality of submunitions, antennae, seismic sensors, acoustic sensors, optic sensors, radar sensors, and the like.
Upon determination of a threat or target of interest, the base mechanism causes the upper body to cant or incline at a pre-defined angle and to rotate in order to orient the associated sensors or munitions in the general direction of the threat. Accordingly, additional data can be collected on the target, and, if desired, a munition launched in that direction.
In conventional field units, the upper body rotates relative to the base at fixed, indexed increments, for example at 9 degree increments, using complicated mechanical systems. In addition, the angle of the inclination is also fixed, for example, to a 45 degree inclination angle. Such units rely primarily on mechanical systems for righting and rotational positioning. They include for example, large-load springs that are used to deploy the feet for righting the unit. While such springs are the most reliable springs available, they tend to be single-use springs and are therefore expensive. In addition, they are difficult to replace and service, and in fact are dangerous for installation personnel, since untimely activation can result in severe injury.
In addition, the rotation mechanism, being fixed at 9 degree indexed increments, does not afford a high degree of precision that might otherwise be desired in modern tracking systems. This applies as well to the fixed 45 degree inclination angle of the upper body. Fixed inclination and rotation angles tend to limit the functionality and effectiveness of these units.